New Delhi: Europa orbits Jupiter, and is slightly smaller than Earth's Moon. Its surface is mostly solid water ice.


Europa may be the most promising place in our solar system to find present-day environments suitable for life beyond Earth, according to NASA. This is because it is abundant in liquid water, energy, and the right chemical elements necessary to support life. Also, Europa's subsurface ocean may contain more than twice as much water as Earth.


Europa Is The Prime Candidate For Life In The Solar System


According to scientists, a salty-water ocean is hidden beneath the icy surface of Europa. This ocean is believed to contain twice as much water as Earth's oceans combined. Europa, like Earth, is believed to have a rocky mantle and iron core.


Thus, Europa is the prime candidate for life in our solar system. For decades, scientists have been enthralled by its deep saltwater ocean. 


However, this Moon of Jupiter is enclosed by an icy shell that could be miles to tens of miles thick, which makes sampling a daunting prospect. 


The ice shell may be less of a barrier and more of a dynamic system, increasing evidence has revealed. It could be the site of potential habitability.


Ice-penetrating radar observations had captured the formation of a "double ridge" feature in Greenland. These observations suggest that the ice shell of Europa may have an abundance of water pockets beneath similar features that are common on the surface. The findings of the study, led by researchers at Stanford University in California, were published in the journal Nature Communications on April 19. 


The results may be compelling for detecting potentially habitable environments within the exterior of the Jovian moon, according to the new study. 


What Could Make Life Possible On Europa?


In a statement issued by Stanford University, Dustin Schroeder, a senior author of the study, said there is a possibility that life has a shot if there are pockets of water in the ice shell. This is because the ice shell is closer to the surface, where one can find interesting chemicals from space, other moons, and the volcanoes of Io, the third-largest of the four Galiliean moons of Jupiter. 


He further said if the mechanism seen in Greenland is how these things happen on Europa, it suggests there is water everywhere.


The researchers analysed polar regions on Earth using airborne geophysical instruments to understand how the growth and retreat of ice sheets might impact sea-level rise. 


According to the statement, much of the study area occurs on land, where the flow of ice sheets is subject to complex hydrology. For instance, there are dynamic subglacial lakes, surface melt ponds, and seasonal drainage conduits.


Formations On Europa Extremely Similar To Features In Greenland


Since a land-based subsurface is so different from Europa's subsurface ocean of liquid water, the researchers were surprised when they noticed during a lab group presentation about Europa that formations that streak the icy moon looked extremely similar to a minor feature on the surface of the Greenland ice sheet. 


Schroeder said that the researchers were working on something totally different related to climate change and its impact on the surface of Greenland when they saw these tiny double ridges. 


When the researchers examined further, they observed that the "M"-shaped crest in Greenland called a double ridge could be a miniature version of the most prominent feature on Europa.


The crests on Europa's surface reach nearly 1,000 feet, and the double ridges appear as dramatic gashes across its icy surface. The crests are separated by valleys about half a mile wide.


Since Europa's surface was photographed by the Galileo spacecraft in the 1990s, scientists have known about the moon's features, but have not been able to provide a definitive explanation of how they were formed.


NASA's Operation IceBridge collected surface elevation data in Greenland from 2015 to 2017, which were analysed by the scientists. In this way, they revealed how the double ridge on northwest Greenland was produced when the ice fractured around a pocket of pressurised liquid water that was refreezing inside of the ice sheet.


This caused two peaks to rise into a distinct shape, the statement said.


Riley Culberg, the lead author of the study, said that in Greenland, this double ridge formed in a lave where water from surface lakes and streams frequently drains into the near-surface and refreezes. 


How Is The Discovery Important?


He further said that one way that similar shadow pockets could form on Europa might be through water from the subsurface ocean being forced up into the ice shell through fractures. He explained that this would suggest there could be a reasonable amount of exchange happening inside of the ice shell.


The ice shell of Europa does not behave like a block of inert ice, but seems to undergo a variety of geological and hydrological processes, the study said. 


There is also evidence of water plumes that erupt to the surface. Since a dynamic ice facilitates the exchange between the subsurface ocean and nutrients from neighbouring celestial bodies accumulated on the surface, it supports habitability.


Gregor Steinbrügge, a planetary scientist at NASA's Jet Propulsion Laboratory, and a co-author of the study, said that people have been studying these double ridges on Europa for over 20 years, but this is the first time researchers were actually able to watch something similar on Earth and see nature work out its magic. He said the team is making a much bigger step into the direction of understanding what processes actually dominate the physics and dynamics of Europa's ice shell.


According to the researchers, their explanation for how the double ridges form is so complex, they could not have conceived it without the analogue on Earth, the statement said.


Culberg said that the findings are opening new possibilities for a very exciting discovery.